Subject: FTP dropping xfers???!!!

From: Sasha Romanosky <[email-masked]>
Date: Tue, 25 Mar 1997 09:47:58 -0700

I have been having complaints from people who tell me that while
they are downloading large files (many Megs), they loose the connection.

I have seen this happen while transferring files via the web;
you sit there and slowly, slowly the file transfers and then suddenly,
mysteriously, the connection drops and you get something link
a "Connection Reset by Peer" message. (Where the "Peer" is
obviously not you.)

Now, I cannot confirm that this is the same problem, indeed, it
may not, but the result is the same.

The problem is reproducible and the only consistenct seems to 
be with very large files, or better yet, transfers which take a very
long
time.

Does anybody have any ideas  - or solutions???

Cheers,
Sasha Romanosky
Internet Applications Specialist
TELUS Advanced Communications
  403.543.2083
  [email-masked]
   www.tac.telus.com

---

From: Michael Brennen <[email-masked]>
Date: Tue, 25 Mar 1997 11:38:19 -0600 (CST)

I too am seeing this, although it seems to be more sensitive on uploads
than downloads for some of my clients.

I think we are seeing the effect of going through overloaded Internet
gateways.  I'm not a TCP/IP protocol guru, but I think this is the effect
of too many lost packets.  Comments from others would be welcome.

   -- Michael

On Tue, 25 Mar 1997, Sasha Romanosky wrote:

> I have been having complaints from people who tell me that while they
> are downloading large files (many Megs), they loose the connection. 
> 
> I have seen this happen while transferring files via the web;  you sit
> there and slowly, slowly the file transfers and then suddenly,
> mysteriously, the connection drops and you get something link a
> "Connection Reset by Peer" message. (Where the "Peer" is obviously not
> you.) 
> 
> Now, I cannot confirm that this is the same problem, indeed, it may not,
> but the result is the same. 
> 
> The problem is reproducible and the only consistenct seems to be with
> very large files, or better yet, transfers which take a very long time.

---

From: Bob Luckin <[email-masked]>
Date: Tue, 25 Mar 97 12:47:46 CST

Sasha Romanosky and Michael Brennen talked about "Connection reset by peer"
problems...

We used to see this on our transfers to and from India and (occasionally)
Europe, but we upgraded the connection and it has largely gone away.
We now have transfers which take longer than 24 hours to these site which
can still complete OK.

I don't know the exact cause, but presumably the problem is related to
reliability of the line - Michael Brennen suggested it may be too many lost
packets.  It's obviously also affected by the loading; if a line - and/or
the server - is heavily loaded the transfers will take longer, which means
a greater chance of seeing the problem before it completes.  

(Sometimes things were so bad that we could FTP to a machine in India,
connect OK, do an "ld", and it would time out before the directory could
be listed...)

Strangely enough, we found that if we telnetted to the remote site, then
ran FTP from there back to our machine (ie. "got" the file from that end
instead of "putting" it from ours, we could sometimes get a transfer to
complete when it would otherwise fail).

Incidentally, we didn't just have this problem with the wustl server - it
happened with the machines' native FTP servers too.

Cheers, Bob
-- 
Bob Luckin      [email-masked]      "Rats live on no evil planet"

---

From: Kent Landfield <[email-masked]>
Date: Tue, 25 Mar 1997 14:02:54 -0600 (CST)

# 
# Sasha Romanosky and Michael Brennen talked about "Connection reset by peer"
# problems...
# 

This is not a wu-ftpd problem I'll bet...

I've run into this a couple times... Years back I paired a 386 with a Sparc10.  
We were constantly seeing "reset by peer" messages on the Sun.  After upgrading
the PC to a 486 it went away. 

Another time I saw it was due to some hardwiring of timeouts one of the 
IP Stack vendors did. The timeout was generated using a clock speed calcuation.
When the software was put on a much faster machine the timeouts happened
quite often. The vendor was red-faced...

Another time I saw it was in a WAN situation where the line was not as 
reliable (or as big) as it should have been.  Traffic spikes that exceeded 
available bandwidth were the problem and once again timeouts bit us.

The point here is that this kind of error can come from various sources
relating to timeouts in the IP stack.  You need to examine what may be the
possible cause.  Look at the systems you're using, the IP stack software 
and the bandwidth its running on.  Chances are the solution is more obvious 
than you realize.

-- 
Kent Landfield                        Phone: 1-817-545-2502             
The Landfield Group                   FAX:   1-817-545-7650             
Email: [email-masked]             http://www.landfield.com/
Please send comp.sources.misc related mail to [email-masked].
Search the Usenet Hypertext FAQ Archive at http://www.faqs.org/faqs/

---

From: Michael Brennen <[email-masked]>
Date: Tue, 25 Mar 1997 14:47:25 -0600 (CST)

The thing that makes me point to Internet gateways/transfer points is that
my equipment here is lightly loaded; both the servers and full T1 are
nowhere near capacity.  Traceroutes frequently seem to find backbone
transfer gateway delays at times that someone is having trouble
{up,down}loading. When I say 'lost packets', I'm more broadly meaning
packets that either never made it through an overloaded gateway or were so
delayed that they were timed out. 

   -- Michael

---

From: Bob Luckin <[email-masked]>
Date: Tue, 25 Mar 97 15:08:20 CST

Kent Landfield said :-
[Re "Connection reset by peer" problems...]
> This is not a wu-ftpd problem I'll bet...

Agreed.  In my posting, I said :-
> happened with the machines' native FTP servers too.

Since it appears that more than one of us have seen it also with non-wustl
servers, it does seem to indicate a more generic problem.

(Good war stories / advice, too, Kent.)

Cheers, Bob
-- 
Bob Luckin      [email-masked]      "Able was I ere I saw Waterloo"

---

From: Michael Brennen <[email-masked]>
Date: Tue, 25 Mar 1997 16:20:59 -0600 (CST)

Given lightly loaded systems and T1 here, how much can I reasonably start
looking outside my own setup to Internet traffic bottlenecks?  I've
thought for some time that the issue is not ftpd per se, but was more a
TCP/IP protocol issue. 

   -- Michael